1. Field
The present disclosure relates to an acoustic wave filter and a method for manufacturing the same.
2. Description of Related Art
As bandwidth specifications for high performance band pass filters have tightened, precise trimming characteristics for piezoelectric resonators are desirable.
Typically, an acoustic filter includes a series resonator which determines the right frequency of a band, and a shunt resonator which determines the left frequency of a band. Conventional trimming processes are performed separately for the series resonator and the shunt resonator using techniques such as, for example, ion beam etching. Alternatively, such trimming processes may be performed as two processes, in which, after the trimming process is simultaneously performed for the series resonator and the shunt resonator, a further trimming process is performed only for the shunt resonator (or the series resonator).
Such trimming processes require a photomask and an additional photo process capable of opening only one of the series resonator and the shunt resonator.
Therefore, fabrication processes such as an additional photomask process, a photolithography process, and the like, are performed on a structure. In other words, such trimming processes require photolithography in two steps. Accordingly, conventional fabrication process for acoustic wave resonators may have a low yield and precision. Improvements in fabrication process are, therefore, desirable.